Possible bug in the template instanciation machinery

[Gabriel Dos Reis <Gabriel dot Dos-Reis at cmla dot ens-cachan dot fr>]

Consider the following:

poivre% cat b.C 
template<class T> struct Y { typedef T X; };

// Primary base
template<class T, class U> struct Base {};

// partial specializations
template<class T> struct Base<T, typename T::X> {};

template<class T> struct Base<typename T::X, T> {};

template<class T, class U> struct Derived : Base <T, U> {};

struct A {};

template<class T> struct Derived<A, T> : Base< Y<T>, Y<T> > {};

int main()
{
    Derived<A, int> d;
}


poivre% g++ -v; g++ b.C
Reading specs from /BASE/dosreis/EGCS/lib/gcc-lib/sparc-sun-solaris2.6/egcs-2.93.15/specs
gcc version egcs-2.93.15 19990405 (gcc2 ss-980929 experimental)
b.C: In instantiation of `Derived<A,int>':
b.C:19:   instantiated from here
b.C:19: ambiguous class template instantiation for `struct Base<Y<int>,Y<int> >'
b.C:9: candidates are: struct Base<typename T::X,T>
b.C:7:                 struct Base<T,typename T::X>
b.C:19: base class `Base<Y<int>,Y<int> >' has incomplete type


>From my understanding of 14.5.4.1/1 EGCS gets it wrong because none of
the specialization matches Base< Y<int>, Y<int> >, so the instanciation
isn't ambiguous at all. It should be considering the primary template. 

-- Gaby

--MAA00288.923480545/ariane.ens-cachan.fr--